Compared to other calculators we've posted, this one is extremely simple. Even if we don't remember the formula for DC heat dissipation in a resistor, a little Ohm's Law and the definition of power can easily create it. On the other hand, forgetting to calculate power ratings, particularly for cathode resistors and RC ripple filters, is one of the most common mistakes designers make. Ditto for placing a heat-sensitive capacitor next to some amp-warming ohms. So hopefully the mere presence of this calculator will serve as a reminder to include heat dissipation concerns in the final design.
The calculator computes the DC heat dissipation in a resistor based on its value and the voltage across it.